So, what is this Oxford comma, and why does it matter? (Hint: there's one in the caption of this post.) You won't get the answer by watching the video above, and listening to the lyrics of a song called "Oxford Comma" by Vampire Weekend, one of my favorite twee bands (the other is Belle & Sebastian). You will by reading this NPR piece by Linda Holmes, whose views on language issues appear virtually congruent with mine (although I do hyphenate "e-mail"). She concludes by noting that all of us who care about such things have our pet peeves. If you've been following this blog for a while--and if you have, God bless you--you know mine.
Update: reader Quin, in a comment below: "A battle rages in my firm over this--it's AP v. Oxford." I'm guessing you're on the Oxford side, Quin, so you may cite the Chicago Manual of Style (16th ed., 2010) 6.18 as support:
When a conjunction joins the last two elements in a series of three or more, a comma--known as the serial or series comma or the Oxford comma--should appear before the conjunction. Chicago strongly recommends this widely practiced usage, blessed by Fowler and other authorities (see bibliog. 1.2), since it prevents ambiguity.